Electron tube circuits



Jan. 2, 1945. 'R. GEORGE ELECTRON TUBE CIRCUIT FiledDec. 51, 1942 INVENTOR BoJ mefi George, BY Wee.

' ATTORNEY rroiirthe@rnulti-electrode type Patented Jan. 2, 1945 *ZUNIIED TSTATESZQ; I

Roscoe H'. George,

Application December 31, 1942; s

;' 5 Claims.

This invention relates 't0;electronic circuits, and rmalltieu arly those.; of the amplifying detector etype; andul iay v also be considered as applyingto =icirciiit .which are used in atransceiver device.

aThe;apparatusandgcircuitherein to be dis-- 212010566315: particularly a rirrreceivingarrangements where weak signal. inpu-ts are to be :IBQBi'VBdYaHd amplified; and wherevsinithe receiving; circuitiis' particularly sensitive. .ti l' th xfiame :time; 1 111161313 113 desirable :and: amplifierarrangement useful as. a detector and for, use inaircraftand :1the:like, =1where ;the-. ;detri-mental efiects or precipitation; static; :suclras yfre uently practically l glisrupts; communication; are substantially j over- 1.

vention i herein to" be disngle gtube :functioningpri- I ;--marily-. as adetector and oscillator arrangement for receiving the signals. ;The tube essentially is:-

having certain of the electrodesz associated" with:.an input circuit; in wewhichrtheremay or may notv be a bufier-tube; as desired, and having othenelectrodes of the-tube connectedwith an oscillatory circuit which, in!" u-rm is connected with the output portion of the btube.

usedv as; a transceiver ar- ".t'Whenf they. device: is wrangement; provision- :isr made for introducing -Essentially,-. the:.::in nlosed: comprises a-zsi iismodulatiorr-signals'upon one coldelectrode of 30Qbytheucoil zfliwhieh-rlia 'tr'file .tube, and-,themfeeding. back energy from the rtoscillatory :circuiticonnected to -otherv cold elec- {ltIlQdES of rtheutube so-thatr the feedback renergy wrisasupplicd to the antenna.

finder-such circumstances, :provision is made qforz'switchingfthe .control circuits bysuitable switchesganged-together, so that for periods of rcreception no feedback energy. is fednto the aniistennas and .forperiods of transmission .no energy from the antennaissupplied-to the control-tube. nccordingly; among the objects of "the -inven-' aaationarare those-"of-providing atransceiver argrangementzwhichsis-particularly: sensitive in .its aoperationand i-whichcis extrernely simple to -ops'erate andzconstmct. wfltherrv'objectsa-of the invention are those of :1 providing-1 a: signatreceivingcircuit and detector 'amplifying:-systemwhich is particularly sensi- :,.'tive, -and: in which stations having -weakpower aerial-located -in t the-frequency spectrum nearby 5 highpower -'stations-' can be distinguished readily {from the high power stations fOtheraobl'ectsr of the invention are to; produce. ea: simplified: electronic tubeicircuit :usableboth I Mon receiving: andrtransmitting; which is "highlydapted,=however, for use 0 11 4 smay :be trme s operationsand "which operates and .is constructedzin anextremelycompact space.

I Another object otrtheiinventionpis thatof: pro- -yidin-g, a method and circuitwith high selectivity for-xefliciently;detecting signals. at low level with- .;=outthe ;use,offregeneration, and, attheisameltime avoiding the snsceptibility -to shock-excitation of high \iQfscircuitsa which; efliectstare particularly I -noticeclr and -i encountered,sitar-instance, in. the

the -present invention is par- 0 case:of, precipitation static,.arisingin connection with? aircraft, l Other objects-and,advantagesiofthel invention t-are those of; overcoming certainv-idefectsz-of the prior art systems aslarerknown, and,- :at thGtSELmG 15 time, providing a highly eflicientoperating cir- --,cuit.- I v I l-i Othemobjects ands-advantages,wilLbecome apparent :frorn a ,consideration of -l the .following specification anda'claimswhen .read in/connec- 'tion with theaccompanying drawing whereinthe ssingle; figure thereonschematicallyrrepresents one v--:fo,rm-of theinvention; i

Referring now to the ,drawingpsignals mayabe ,.---received.--ortransmitted .fromaani ,antenna'r ar- '25."rangement 2 I qwhich'aispconnected to .ground 22 -byswaycry-the; antenna couplingv -coil- :23. Under conditions-whens. signals areto -be received, the --antennascoilw2 3- serves. as: a primary winding of l. a F t-transformer ewhosee I secondary is represented s eonemterminalwhereof connected-,-rto theeconductor. 2,5, and: thez-other terminal connected .1305. ground-crat 22. =.-=When theaarrangement is used for transmission-.purposes-ethen the antenna coil 23-serves as; a l-secondaryn'winding r rand receives its energy fromethev =-coi1 r-i'hwhich" has'laone'raterminal .-connected aoaconductor-28; and dihecther. terminal connected :to ground at -22. Inwvell known-manner; "shielding; convention- 40 ally :indicatedtbyathevdotted outline -29,- is pro- -vided1for-v all of theyantenna' iand'menergy transfer -coils.fi I

Assuming now,

that the; arrangement herein v disclosed-iris? :td: bev-rusedt for sreception; thezrthe d byzmeans -of:- a--- suitable connected in shunt there- 30-is-preferably- (although er-atesimultaneousnot' necessari-lyl'ganged to=op -1y": vn -th -;ccndensers: liiiwandv -62, later. to be; deesc-r-ibedx With-thecoil and condenser 30-tuned --.to. any; desired resonant -trequency, it is apparent J that-zenergyimay then bered by way of the cond t "f25i through-the contact- 'point: 3| -switcharm-32-:tm a-wconductor'afl which feeds its fi l yyto the" control .-.electroder34 of the. thermcontrol electrode 34 of arrangement later will be made.

trum in a region very close to ionic device 35. Under such circumstances, and assuming conditions of reception, the switch arm 32 is in its upper contact position, as indicated, so that it rests against the contact pint3l. Similarly, since the device is assumed, in the diagrammatic showing of the drawing, to be in a state for receiving energy, the upper switch arm 36 is also adapted to rest against its upper contact point 31 rather than against the lower contact point 38,, so that-here is circuit to the coil 21. y

In order to ensure this state of operation for conditions of reception, the switch arms 32 and 36 are moved in unison by means 01' the uni-.

provided an open control, conventionally shown by the'dotted line 39, so that both switch arms move;

against either the upper or the lower points. i

For. conditions or transmission,obviously-the together contact switch arms 32 and 36 will'rest against the lower contact points 48 and 38 respectivelyyso that energy from the conductor 41 may be fed to the coil 21, and, similarly, energy introduced'into the transformer secondary 42,1which has one terminal connected to the contact point 48 andthei other terminal connected to ground 22 may be fed into the conductor 33 and thence, upon the the thermionic device '35. For this state 01' operation, input signal energy which, for purposes of illustration may be as sumed to be voice energy or audible signals, is applied to the pick-up device, conventionally represented as the microphone l3, and fed byway of the transformer primary 44 into the transformer secondary 42. g

Further reference to the transmitter 'form of For the present, it is assumed that signals are to be receivedso that the switch arms, indicated at 32 and 36,are agalnstthe upper contacts 3| and 31, so that" signals received at the antenna 2i will be fedto the tube 35 and there will be an open circuit to the winding (inductance) 21;

It will be seen that under some circumstances it may be desirable to provide for preventing any re-radiation from the system, which would be particularly desirable where energywas to be picked up from a station of very weak 'power which is radiating energy inthe frequency jspecthat ol astatlon nearby which radiates energy at relatively high power. and which latter station might even be so strong as to give ordinary power detection whether desired or not. Under such elr'cumstances. it is obvious that a buffer tubelmay" be inserted in the lead 25 between the resonant circuit com rised of the coil 24 and thef'condenser 30, so that received energy will be'fedby way of an amplifier, not shown. into thethei'mL quencies, and

then fed by way of the resistors 5i and 52, which are bridged by suitable capacities 53 and 54 so as to apply the necessary operating potential to the electrode member 48. Under these conditions, signals passing beyond the electrode 48 are applied to the #3 grid 55, With the #2 grid 48 serving substantially as a virtual cathode for the second section of the tube which will now comprise, in addition to the electrode 48, the electrode 55, the electrode .48, the suppressor electrode 56 and the anode or plate element 51.

For the purpose of generating oscillations and to provide the necessary heterodyning action, suitable oscillatory circuits are connected between the anode or plate 51 and the electrode member 55. These oscillatory circuits comprise the combination of the inductance element58 and the capacity 59 connected in parallel therewith, and which are c'onnectecl to the anode 'or plate 5'l'of the thermionic device 35 by way of the conductor fifl, and a second inductance element Bi and parallely connected capacity element 62, which is connected to the electrode 'member by way of the conductor 63.

The opposite ends of each of the resonant circuits comprising the inductance 58 and the-capacity 59, and the inductance BI and capacity 62 are connected together by way of the condenser 64, and the inductance elements 58 and 6! are preferably coupled together. e

Suitable direct current voltages 'for the plate or anode 5'! are applied by way of the lo-ad 'resistor 65 which connects to the positivetermin'al 50 through the resistor 5|. I In' order to provide for by-passing high frealso to provide a bias for the electrode 55, there is connected a resistor element 67 between the upper end of the oscillatory circuit comprising'the inductance Bi and the condenser 62, and the element 61 connects to ground 22, as indicated. The usual by-pass condenser 68 shunts the resistor 61, and output energy; as

' it is developed across the oscillatory circuit, may be then taken from across the load resistor 65 by onic device 35 and any re-radiation will be prevented. However, for purposes of illustration, the inclusion of the additional amplifier fbecoi'n'es completely'immaterial.

Therefore, it will be assumed that thej co'nnections are as shdwngand, accordingly, the'fc'athode Y 45 of the thermionic device- 35 is assumed to be way of the coupling condenser 69 connected to the output terminal 10, or, Where an output of the opposite polarity is desired, output signals may be derived by coupling through a condenser, such as the condenser 69, to the terminal point H across the resistor 61, as indicated.

For simplicity of operation, the variable condensers 30, 59 and 62 are preferably ganged together and operate in unison by means of the uni-control schematically represented by the dotted line 13. This makes the circuits comprising the condensers 30, 59 and 62 and'tl'ie inductances 24, 58 and 6| respectively. all tune simultaneously, as indicated. Suitable shielding for the coils 58 and 6| as Well as the pick-up coil 14 later to be described, is provided by the schematically indicated shielding l5.

Under conditions where it is desired to transmit from the system rather than to receive, the switch arms 32 and 36 are thrown againstthe lowermost contact elementsor points 46 and 38 softhatanow the coil and thecondenser are disconnected.-" from "thecontrol electrode I r #1 grid 3 l,. "and, instead; the-pick-up device '43 .=is connected-thereto. Under -these conditions energy isfed from the inductance 58 to the resonant circuit comprising the inductance element-and-the capacity ielement t"iilg-intothe coil =14; with the inductance 58 -serving ,=:-asthe primary and theacoil' 14 as the secondary,

:- and" thence, & this energy,- unden such circumstances, iiieeds through the conductor 4 I "the 7 switch: arm l36 to the lower 3 contact point: 38 J and eintotthen-conductor to feed into the antenna?! wby' way ofwgthe co pling provided between 'the --;iwindings '21. and .123 respectively. At "the: same :attime; modulationsignalsare applied: to 'fthe-COII- trolielectrodeifl of' the tube by way of the-pick- :up device 113 and the transformer windings M and 42 through-.tthe; contact=pointa to the switch :arm: 32;: and-ithenceg by wayof the conductor 33, .1250 'thattheenergy output inthe oscillatorsection of the ,tube, as it appearsin- .the'winding 114, will be modulated in accordance =withithe modulations appearing on'the :pick-eup device 43. At the same time',-however;.no energy is fed fromthe winding ii-into the-w-inding which could betransfer-red to the controlelectrode 34 because the switch arm 1:32 is removed from the contact 3|.

-It .-is,- .of acourse apparentithat there 1 is preferably a .:relatively :tightr couplingv between the windtings: .58 and; filrnandithe resonantcircui-ts 58- and 1.159 on..thex,one-ihand; for instance, and- 6 I: and r62 3.1011 1118'. other ;hand .tshould be tuned to approxi- :1-matelyresonancezwith:the signal frequency which i-it' is: desirechtoreceive, and,;i accordingly; :it will .be seen thatztherreceivedisignal is .really substanxtiallygin phase-with the. 0SCl118t01cWhl'Ch' is; tuned to the carrier. However, even if they oscillator is notsexactly.tuned'.tofthecarrier, it will substantially lock in on the proper frequency, beat frequencies may be developed. However, where the variance becomes too great, the oscillator will not lock in at the proper frequency of its own accord, and where beats are developed, then the beat frequency is high and is not heard. Wherever the oscillator locks in with the carrier, the output energy, as it appears at either the terminal points H or 10, is of a useful nature, and stations of relatively weak intensity, even though located in the spectrum relatively near high power stations, are readily distinguishable.

Considering now, further, the operation of the system and particularly the operation as applied to reception, the incoming signal, as selected by the tuned circuit 24-30, is fed through the conductor 25, the switch arm 32 and the conductor 33 to the #1 grid 34 of the tube 35. The portion of the tube including the #1 grid 34 and the #2 grid 48, which latter element acts as an anode for the first section of the tube, amplifies the signal. In this way, any electron current which passes through the #2 grid 48, where it can be acted upon by the #3 grid of the oscillator circuit, already has the amplified incoming signal riding upon it, Consequentl if the oscillator circuit is tuned to approximately the same frequency as that of the received signal, there'is a very strong tendency for the oscillator to lock in with the ripple on the electron current caused by the received signal energy. Under these circumstances, if the oscillator grid, that is, the #3 grid 55 in the tube 35, is suitably biased and the proper amount of energy is' fed to it from the oscillator circuit, the plate current of the oscillator tube section will be driven to zero during the although negative-swingon the grld. *"During the-positive swing-oi the'oscillator grid; the plate current has j thepositive peaks of the amplified signal riding ori-i it and sinceithe negative portion of the recei-ved-signals: has been eliminated, the signal is erficiently detected. Furthermore; if the oscillatorgrid :is properly biased; it can be seen that amplification takesz place,:as in the first detector of! asuperheterodyne.

Therefore; withthe arrangementdisclosed,-it is believed that' the signal: can be-considered as twice amplified. At thesameitime, linear-detection and highzselectivityi-is provided; so: long. as the inter- -::ieringsignals arenottsufiiciently strong to cause sy detection action as the #1 grid 34 .ofrthetube 35. 'i'Thehighselectivity occurs, ittis thought,'- by -(vir- ---tue-- p nly v-twhen -the' :local oscillator :is :operating: substanrrtia-lly exactly ateithe carrier. frequency; and-in g( =ph3ise-Wlththe carrier.

Certain modifications of the invention of course: areiobviousand -wil1-- become: apparent to z- -those skilled: in the art -towhich' the invention is directed; and itis'*-=believedthat-any--and: allof these modific'ations,---such as "fall fairly within the W spirit and scope of what-has herein'been set forth, -may'.be made-provided they fall fairly within the --scopeof what-ishereinafter claimed.

i Having-described my-invention,- what I claim Jill new and" desire, 130 haveprotected by Letters Patent'is:

1 12*In ---combination,"-an antenna member, r a multi-electrode thermionic device including a -ea'th0de, ananode and a* plurality of additional cold e1ectrodest tunedjnputmeans-to supply sig- ---na1 energy upon -one of thecoldelectrodes of -said thermionic device law-control "the electron WCllIIBIliFflOW from the cathode ;to another "of the cold 1 electrodes, a feedback oscillatory "circuit tuned to substantially -the-input' frequency and connected between the anode and another of the cold electrodes of said thermionic device, a load circuit connected to derive energy from the oscil- 'latory circuit, and means for influencing the current flow in the oscillatory circuit by electronically coupling the output signal energy from the said first portion of the thermionic device into the portion of the device influenced by the oscil- 50 latory circuit.

2. In combination, a receiving antenna member tuned to receive modulated signal energy of a predetermined frequency, a multi-electrode thermionic device including a cathode, an anode and a plurality of additional cold electrodes,

means to supply the received signal energy upon one of the cold electrodes of said thermionic device to control the electron current flow from the cathode to another of the cold electrodes and thereby to provide an am lifled signal output, a

feedback oscillatory circuit connected between the anode and another of the cold electrodes of said thermionic device, means to tune the oscillatory circuit to a frequency substantially corre- 5 'spondingto that received, a load circuit connected to derive energy from the oscillatory circuit, means for subjecting the current flow in the oscillatory circuit to the influence of the amplified signal current to provide for detecting the signal current by electronically coupling the output signal energy from the said first portion of the thermionic device into the portion of the device influenced by the oscillatory circuit, and means to derive amplified-detected output signal energy from the load circuit.

, the oscillatory circuit thermionic device including a 3. In combination, an antenna member,-. a multi-electrode thermionic device including a cathode, an anode and'a plurality of additional cold electrodes, a source of signal energy, means to supply signal energy from the source upon one of the cold electrodes of said thermionic device to control the electron current flow from the oathode to another of the cold electrodes, a,- feedback oscillatory circuit tuned to a predetermined carrier frequency connected between the anodeand another of the cold electrodes of said thermionic device, a load circuit connected to derive energy from the oscillatory circuit, means to feed said energy to the antenna, and means for influencing the current flow in the oscillatory circuit by electronically coupling the output signal energy from the said first portion of the thermionic device into the portion of the device influenced by whereby modulations of the carrier frequency energy are applied to the antenna.

4. In combination, a receiving antenna member tuned to receive modulated signal energy of a multi-electrode cathode, an anode and a plurality, of additional cold electrodes, means to supply the received signal energy upon one of the cold electrodes of said thermionic device to control the electron current flow from the cathode to another of the cold electrodes and thereby to provide an amplified signal output, a feedback oscillatory circuit connected between the anode and another of the cold electrodes of said thermionic device, means uni-controlled with the tuning of the receiver circuit to tune the oscillatory circuit to a frequency substantially corresponding to that received, a load circuit connected to derive energy from the oscillatory circuit, means for subjecting the current flow in the oscillatory circuit to the influence of the ama predetermined frequency,

vice influenced by the oscillatory circuit; and -means-to derive amplified-detected outputsignal energyfrom theload circuit.

5. In combination, an antenna, a multi-electrode thermionic device having at least a cathode,

an anode and a plurality ofcold electrodes, a first input circuit including a tunable resonant circuit to receive energy from said antenna; a second input circuit including a source of lation signal energy, switching means to supply signal energy from one only of the saidinput circuits upon one of the cold electrodes of said thermionic device to control the electron flow between the cathode and another of saidcold electrodes for signal energy amplification, a plurality of coupled oscillatory circuits connected to the anode and another of said cold electrodes of said tube whereby oscillations are produced by said tube in said circuits and the output signal amplified energy from the first portion of the tube is electronically coupled to influence the oscillations developed, a first load circuit and a second load circuit, said second load circuit being cou- Dled to feed energy into the antenna, and a second switching means for connecting the second load circuit to the antenna'during the time periods when the second source ofsignal energy is connected to the control electrode of the thermionic device andfor disconnecting the second load circuit from the antenna at periods when the first of said signal input circuits is connected to the control electrode to supply energy from the antenna to the control electrode of said thermionic device. ROSCOE H. GEORGE,

mo du- 

